1. Field of the Invention
The present invention relates to an improved method of forming thermal transfer dye images by means of recording elements comprising heat-diffusible dye or heat-diffusible dye precursor.
2. Description of the Prior Art
Several methods are known for transferring heat-diffusible dye from an overall heated element comprising such dye in combination with an image-wise distribution of photopolymerized areas and unpolymerized areas onto a receiving element, the photopolymerized areas inhibiting or reducing the diffusion of the dye to the receiving element.
It is for instance known from U.S. Pat. No. 3,245,796 to use a photopolymerizable element comprising a mixture of an .alpha.,.beta.-ethylenically unsaturated compound and a sublimable dye for forming by photo-initiated addition polymerization of said .alpha.,.beta.-ethylenically unsaturated compound a mask containing insoluble areas, through which the passage of the sublimable dye is impeded, and to overall heat the mask-containing element while in contact with a receptor surface so that transfer of the sublimable dye from the non-polymerized areas to the contacting receptor surface can take place.
In U.S. Pat. No. 4,587,198 a process has been described for providing a colour image comprising exposing a photoresist-type material comprising in the order given a support, a vapour-deposited dye or pigment layer, and a radiation-sensitive coating to an image-wise distribution of radiation that alters the solubility and/or permeability of said coating and uniformly heating said material while in contact with a receptor to evaporate said sublimable dye or pigment and deposit it on the contacting receptor.
In EP-A 362,827 an image-forming method has been described, which comprises the steps of using an image-forming medium containing a heat-diffusible colouring matter, a polymerizable polymer precursor, and a polymerization initiator, causing the polymerizable polymer precursor to image-wise polymerize, and heating the imaged medium while in contact with a receiving medium to diffusion-transfer the heat-diffusible colouring matter thereto, the heating being such as to satisfy the formula Tg1.ltoreq.Ttrans.ltoreq.Tg2, wherein Ttrans represents the temperature of the image-forming medium, Tg1 represents the glass transition temperature of unpolymerized areas, and Tg2 the glass transition temperature of polymerized areas.
The prior art materials and methods used so far often have the disadvantage of providing an unwanted hue or fog in the background areas.